Usually, gear wheels made as loose wheels of various gears of a transmission are connected in a rotationally fixed manner to a transmission shaft on which the loose wheels are arranged by way of synchronizers. With the synchronizers, when a gear of a transmission is engaged, rotational speed differences, between a loose wheel to be engaged and the transmission shaft associated with the loose wheel, are first equalized by the action of friction. When equality of speed has been reached, between the loose wheel and the transmission shaft, there is no longer any dynamic friction torque and a locking gear releases a claw of a synchronizer provided for the engagement of the loose wheel so that the desired gear can be engaged with positive interlock.
The disadvantage of such synchronizers is that they entail undesirable manufacturing effort and are, therefore, expensive to produce, because they are made with frictional, locking elements and claws.
Alternatively to the synchronizers described above, transmission devices are known from practice for the engagement of loose wheels, which are made with simply designed, frictional shift elements, such as lamellar shift elements. To maintain such shift elements in an engaged condition, generally, these must be acted upon by an actor with a holding force sufficient to maintain the engaged condition of the shift elements, which is produced mechanically, magnetically, pneumatically or hydraulically. However, this holding force that has to be applied constantly by an actor disadvantageously reduces the overall efficiency of the transmission.
From CA 2 451 899 A1 a frictional shift element with self-reinforcement is known, which remains in the engaged condition without a holding force that must be applied separately, because of an applied torque.
However, this has the disadvantage that the connection, between a component mounted to rotate in a shaft and the shaft itself, is made by positive interlock so that, in relation to driving comfort, the component can only be coupled to the shaft unproblematically when the rotation speed difference, between the component on a loose wheel and a shaft, is small. If engagement or rotationally fixed connection of the component to the shaft is required when the speed difference between the component and the shaft is large, the positive connection, to be formed by the self-reinforcement, between the shaft and the component results, because of the very short shift time in an impulse exchange with high torque peaks, leading to a deterioration of the driving comfort and to undesirably high component loads.
In addition, from DE-PS 410 285, a hydraulically actuated friction clutch for speed-change transmissions is known, whose structure is compact. In this case, a clutch disk of the friction clutch, by way of which a loose wheel arranged on a shaft can be connected in a rotationally fixed manner on the shaft, is acted upon directly from inside the shaft with a hydraulic pressure required to fix the loose wheel. The clutch disk is displaced in translation on the shaft by the action of the pressure to engage a gear.
Since a pressure space associated with the clutch disk, which is acted upon by the hydraulic pressure, is formed between gear wheels arranged to rotate on the shaft, low-friction and effective sealing can only be achieved by considerably elaborate seals. For that reason, high energy consumption is required in order to maintain the axial force for the rotationally fixed connection of a loose wheel to the shaft. Moreover, because of the large number of seals, the arrangement is characterized by high friction losses which again have an adverse effect on the overall efficiency of a transmission since the friction forces demand an increase of the actuation forces.
Accordingly, the purpose of the present invention is to provide an inexpensive device for the rotationally fixed connection of a shaft to at least one component mounted to rotate on the shaft, which improves the overall efficiency of a transmission by comparison with conventional transmissions.